Movable barrier operator auto-force setting method and apparatus

ABSTRACT

A movable barrier operator having a motor controller ( 10 ) and motor ( 11 ) that control selective movement of a movable barrier ( 12 ) also has an obstacle detector ( 14 ) that utilizes an automatically determined excess force threshold value to permit reliable detection of an obstacle under a wide variety of operational circumstances, including changing physical circumstances, aging components, temperature variations, and motor runtime. In a preferred embodiment, a characteristic force value for the system is frequently updated as a function of actual measured force requirements (and further compensated, pursuant to various embodiments, with respect to other conditions such as temperature and motor runtime). This characteristic force value is then utilized to determine the excess force threshold value.

CROSS REFERENCE TO RELATED APPLICATION

This is a division of prior application Ser. No. 10/335,199, filed onDec. 31, 2002 now U.S. Pat. No. 6,870,344, which is hereby incorporatedherein by reference in its entirety.

TECHNICAL FIELD

This invention relates generally to movable barrier operators and moreparticularly to auto-force setting.

BACKGROUND

Many movable barrier operators monitor applied force (typically bymonitoring a parameter that varies as a function of force) ascorresponds to movement of a movable barrier and use such information todetermine when the movable barrier has encountered an obstacle (such asa person or item of personal property). Upon sensing such an obstacle,the operator will typically initiate a predetermined action such asreversing the movement of the barrier. In particular, the operatorusually compares present applied force against a threshold thatrepresents excessive force to identify such an occurrence.

Unfortunately, a factory-set static excessive force threshold willtypically not provide satisfactory results under all operatingconditions and/or for all installations. The reasons are numerous andvaried. The physical dimensions of a given installation can varydramatically (both with respect to barrier travel distance and barrierweight as well as other manifest conditions) and these physicalconditions can and will in turn impact the amount of force required tomove the barrier. The physical interface between the barrier and itscorresponding track or pathway can also vary, sometimes considerably,over the length of barrier travel. Such variations can each, in turn, beattended by significantly varying force requirements. Temperature, too,can have a significant impact on necessary force, as temperature (andespecially colder temperatures) can alter the physical relationshipsnoted above and can also significantly impact upon at least the initialoperating characteristics of a motor as is used to move the barrier.Force needs, measurements, and/or behaviors can also vary with respectto time, as the physical conditions themselves change, as the motorages, and even with respect to how long a motor has been recentlyoperating.

To attempt to accommodate such circumstances, many movable barrieroperators have a user-adjustment interface (usually one or twopotentiometer-style knobs) that a user or installer can manipulate toadjust allowed applied force during one or more directions of barriertravel. Unfortunately, even when used correctly, force settingsestablished in this way can become outdated. Another solution has beento provide a learning mode during which a movable barrier operator canmonitor force conditions during movement of the barrier and use suchinformation to automatically establish an excess-force threshold to beused during subsequent normal operations. Unfortunately, again, forcesetting values established in this way can become outdated (andsometimes within a short period of time).

BRIEF DESCRIPTION OF THE DRAWINGS

The above needs are at least partially met through provision of themovable barrier operator auto-force setting method and apparatusdescribed in the following detailed description, particularly whenstudied in conjunction with the drawings, wherein:

FIG. 1 comprises a block diagram as configured in accordance with anembodiment of the invention;

FIG. 2 comprises a flow diagram as configured in accordance with anembodiment of the invention;

FIG. 3 comprises a graph depicting illustrative force behavior;

FIG. 4 comprises a flow diagram illustrating detail in accordance withan embodiment of the invention;

FIG. 5 comprises a graph illustrating certain particulars as accord withan embodiment of the invention;

FIG. 6 comprises a flow diagram illustrating detail in accordance withan embodiment of the invention;

FIG. 7 comprises a graph illustrating certain particulars as accord withan embodiment of the invention;

FIG. 8 comprises a graph illustrating certain particulars as accord withan embodiment of the invention;

FIG. 9 comprises a graph illustrating certain particulars as accord withan embodiment of the invention;

FIG. 10 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 11 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 12 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 13 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 14 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 15 comprises a flow diagram illustrating detail in accordance withan embodiment of the invention;

FIG. 16 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 17 comprises a block diagram as configured in accordance with anembodiment of the invention;

FIG. 18 comprises a graph illustrating certain particulars in accordwith an embodiment of the invention;

FIG. 19 comprises a flow diagram illustrating detail in accordance withan embodiment of the invention;

FIG. 20 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention;

FIG. 21 comprises a graph illustrating certain representative phenomena;

FIG. 22 comprises a flow diagram illustrating detail in accord with anembodiment of the invention;

FIG. 23 comprises a block diagram as configured in accordance with anembodiment of the invention;

FIG. 24 comprises a flow diagram illustrating detail in accord with anembodiment of the invention;

FIG. 25 comprises a flow diagram illustrating detail in accord with anembodiment of the invention;

FIG. 26 comprises a flow diagram illustrating detail in accord with anembodiment of the invention;

FIG. 27 comprises a flow diagram illustrating detail in accord with anembodiment of the invention;

FIG. 28 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention; and

FIG. 29 comprises a graph illustrating certain particulars as accordwith an embodiment of the invention.

Skilled artisans will appreciate that elements in the figures areillustrated for simplicity and clarity and have not necessarily beendrawn to scale. For example, the dimensions of some of the elements inthe figures may be exaggerated relative to other elements to help toimprove understanding of various embodiments of the present invention.Also, common but well-understood elements that are useful or necessaryin a commercially feasible embodiment are typically not depicted inorder to facilitate a less obstructed view of these various embodimentsof the present invention.

DETAILED DESCRIPTION

Generally speaking, pursuant to these various embodiments, an automaticforce-setting capability permits regular (or essentially constant)updating of one or more force thresholds that are used, for example, todetect an excess application of force as ordinarily associated withobstacle encounters. This capability exists compatibly with, or without,concurrent availability of an automatic force-setting learning mode ofoperation and/or user-manipulable force-setting controls.

In general, actual exerted force (typically as ascertained viamonitoring of a corresponding parameter, such as motor current) informsthe automatic updating/changing of the force-setting(s) value(s) (ingeneral, for ease of presentation, only a single force-setting value orthreshold will typically be mentioned herein with it being understoodthat such a reference includes both the singular and plurality of suchvalues or thresholds). As actual exerted force increases or decreasesover time and/or with circumstances (such as changing physicalconditions and/or ambient temperature), the force-setting value can besimilarly changed to aid in ensuring that the force-setting valueremains relevant to present operating circumstances.

Such changes are effected in a variety of ways pursuant to these variousembodiments. In one embodiment, no changes are made to a presentforce-setting value when a present force measurement is not sufficientlydifferent from a present point of comparison. In another embodiment, theforce-setting value is changed in substantially identical correlation toa given present force measurement (for example, by causing acharacteristic force value that is used to determine an excessforce-setting threshold to be rendered substantially equal to a presentforce measurement). Pursuant to yet another embodiment, such acharacteristic force value (and/or a resultant excess force threshold)is altered in a step-fashion when, for example, a relatively significantgap exists between the characteristic force value and the present forcemeasurement. So configured, an automatically determined force-settingvalue can track actual force changes while avoiding relatively pointlessalterations and/or over-reacting to any particular anecdotal actualforce measurement.

In various embodiments, a single force threshold can be automaticallydetermined for an entire length of travel, or multiple thresholds can besimilarly calculated for corresponding portions of the travel time whensignificant differing force behaviors are detected. In yet otherembodiments, a changing threshold mechanism can be provided throughidentification of a linear or non-linear curve that substantially fitsand accommodates the behavior of the installation itself and/or throughdetection and corresponding accommodation of a ringing behavior thatcharacterizes a given installation.

In other embodiments, various other limits and/or thresholds can beutilized to control and/or detect conditions of possible concern. Forexample, an upper limit can be placed on the extent to which an excessforce threshold can be adjusted pursuant to these various embodiments.Thresholds can also be used to detect stall conditions and/or likelycomponent and/or system faults.

In addition to (or supplemental thereto) automatically altering a forcethreshold or value as a function of actual perceived force readings,pursuant to other embodiments, such thresholds/values can be modified asa function of temperature and/or runtime history of the motor(s) thateffect movement of the moveable barrier. Pursuant to a preferredembodiment, such alterations are substantially limited to use duringlower temperature conditions, as higher temperatures tend to impactconditions of interest with less severity. Pursuant to another preferredapproach, when a significant temperature drop of interest has occurredbetween a present setting and a previous occurrence of interest, alarger alteration to a force value or threshold may be permitted thanunder other circumstances to thereby more quickly accommodate likelynormal behavior of the overall system.

These various embodiments provide a variety of resultant combinationsthat readily suit a wide variety of expected operating conditions anddesign criteria. In general, these embodiments permit a force thresholdvalue to be automatically calculated on a regular (or continuous) basis,in conjunction with or apart from a learning mode of operation, and in afashion that tends to encourage relatively constant availability of arelevant and suitable threshold value. Various operating conditions canchange slightly or significantly, suddenly or slowly, without undulyadversely impacting the availability of relevant and useful forcesetting or settings.

Referring now to FIG. 1, a motor controller 10 couples to andselectively controls a motor 11. The motor 11 in turn couples via anappropriate mechanism (not shown) to one or more movable barriers 12(such as, but not limited to, garage doors (both single-piece andsegmented), sliding and swinging gates, rolling shutters, and so forth).The motor controller 10 comprises, in this embodiment, a programmableplatform (having, for example, a microprocessor or programmable gatearray or the like) that can be readily programmed to serve as describedherein (of course an appropriately configured static platform can beutilized as well if desired). Such elements are generally wellunderstood in the art and hence additional description will not bepresented here for the sake of brevity and the preservation of focus.

A force sensor 13 couples to monitor one or more parameters that areindicative of force as exerted by the motor 11 to effect desiredmovement of the movable barrier 12 (if desired, of course, a pluralityof force sensors can be employed to provide either redundant monitoringcapability and/or multi-point or multi-parameter monitoring). In thisembodiment, the force sensor 13 comprises a mechanism (such as acurrent-sensing resistor) to detect current flow through the motor 11(in general, current flow through a motor will correspond to loading andhence will tend to provide a relatively reliable indication of forcebeing exerted by the motor). In alternate embodiments the force can bemeasured by velocity, a strain gauge, or any other force detectionmethod.

The output of the force sensor 13 couples to an obstacle detector 14 andfurther serves to inform an automatically determined excess forcethreshold value indicator 15 (as described below in more detail). Soconfigured, the obstacle detector 14 can compare force as sensed by theforce sensor 13 with an excess force threshold as provided by the excessforce threshold value indicator 15 to detect when the motor 11 at leastappears to be outputting excess force (thereby indicating the possiblepresence of an obstacle in the path of the movable barrier).

In a preferred embodiment, the excess force threshold value indicator 15automatically determines the threshold value in response to actual forceas sensed by the force sensor 13. Such determinations can be made on aregular or irregular basis, but in a preferred embodiment are made atleast once during each full traversal of the movable barrier. Ifdesired, a typical user-initiable dedicated learning mode 16 can also beprovided, such that an initial excess force threshold value can beinitially determined via such an approach. Regardless, however, in apreferred embodiment, the excess force threshold value indicator 15serves to determine initially (when needed) and to continually updatethereafter during normal operating modes of operation the excess forcethreshold value. So configured, these teachings are suitable for useboth with and without a platform having such a learning mode.

Similarly, it should be noted that such a system could be provided witha user-accessible excess force threshold value adjustment interface (notshown) as well understood in the art. Though such an interface can beprovided, when properly configured, these teachings should, at least ina significant number of instances, mitigate against the need to make anysuch provision.

In a preferred embodiment, the excess force threshold value indicator 15automatically determines a characteristic force value (in response, atleast in part, to the force sensor) that corresponds to this giveninstallation. The excess force threshold value can then be determined asa function, at least in part, of the characteristic force value. Forexample, the characteristic force value is summed with a predeterminedoffset in a preferred approach to thereby determine the excess forcethreshold value. So configured, the motor 11 can apply force in excessof the characteristic force value without the obstacle detector 14interpreting such an event as an obstacle so long as the force over andabove the characteristic force value does not exceed the predeterminedoffset.

In a preferred embodiment, it is the characteristic force value that theoperator automatically adjusts to reflect changing conditions regardingthe application of force during normal operation. The predeterminedmeasure is then readily combined with the frequently updatedcharacteristic force value to yield a correspondingly updated excessforce threshold value.

So configured, and referring now to FIG. 2, during a normal mode ofoperation (and regardless of whether a user-initiable learning mode ofoperation has been earlier applied) the operator will monitor 21 a forceparameter (as detected by the force sensor 13) and automatically update22 the excess force threshold value. (As will be shown below in moredetail, the operator may use a single threshold value or, in thealternative, a plurality of thresholds may be used and applied atdifferent times during movement of the movable barrier. In a preferredembodiment, the update will occur at the end of a movement cycle, thoughanother time or times could be utilized when and as appropriate to agiven implementation.) As noted above, in a preferred embodiment, theoperator will effect such updating by automatically changing acharacteristic force value in response to the monitored force parameterand then using the updated characteristic force value as a basis fordetermining an updated excess force threshold value. The operator thenuses 23 the updated excess force threshold value to determine whenexcess force appears to be applied by the motor 11. When the operatordetects 24 the application of apparent excess force, one or morepredetermined actions 25 are initiated (for example, movement of themovable barrier can be halted or reversed, alarms can be activated, anincident log can be updated, and so forth).

With reference to FIG. 3, a not untypical force response 30 for a such asystem will typically exhibit a significant peak 31 during an initialperiod 32 of activation (or, more particularly, the motor will initiallyspike in a manner as suggested due to inertia and other factors,therefore causing the apparent force to appear to reach a correspondingpeak). For many purposes, it may be desired to essentially ignore theforce response 30 for a predetermined period of time T₁ (such as, forexample, approximately one second) such that these peaks do notinfluence the resultant characteristic force value TH_(c) and/or theexcess force threshold value.

As depicted in FIG. 3, the characteristic force value TH_(c) comprises asingle value that is used as described earlier to determine acorresponding excess force threshold value during the entire period ofmovement of the movable barrier (from, for example, an open position toa closed position or from a closed position to an open position). Asdepicted, the characteristic force value TH_(c) appears to beconsiderably larger than the bulk of the actual measured force response30. Pursuant to these teachings, many of the embodiments taught hereinwould tend to reduce the characteristic force value TH_(c) over time tomore closely approximate the actual force response 30 (presuming, ofcourse, that the actual force response 30 itself did not changeappreciably during this period of change and re-characterization).

It is unlikely, of course, that such an actual force response 30 will beutterly flat; instead, there will usually be peaks and valleys. To theextent that such undulations, and especially the peaks, do not varysignificantly from what otherwise amounts to an average value for theforce response 30, there is no particular value in reflecting such minorvariations in the characteristic force value TH_(c) or the resultantexcess force threshold value. A process to permit such a result appearsin FIG. 4. As noted above, the force response 30 will typically beginwith a brief large peak. Therefore, the process will preferably begin bywaiting 41 for a minimum time (such as time T₁ as suggested in FIG. 3)before responding to the force response 30. Subsequent to this optionalinitial window of time, the process then detects the highest forceresponse peak and measures 42 that peak force F_(p). The process thendetermines 43 whether that peak force F_(p) falls within a predeterminedsmall range. When true, meaning that only negligible peak excursionshave been observed with respect to the characteristic force valueTH_(c), the update process can simply conclude 44 without anysubstantive change being made to the characteristic force value TH_(c)and/or the excess force threshold value.

In this embodiment, the range is established as a small amount X that isadded or subtracted from the characteristic force value TH_(c). As shownin FIG. 5, this results in an upper limit 51 equal to the characteristicforce value TH_(c) plus the amount X and a lower limit 52 equal to thecharacteristic force value TH_(c) less the amount X. So configured, whenthe highest peak of the actual force response 30 remains within thisrange, the update process can conclude without resultant change to thevalues of interest.

With reference again to FIG. 4, when the actual force response 30 has apeak that falls outside the indicated range (being either higher thanthe upper limit 51 or less than the lower limit 52), the process canagain automatically change 45 the characteristic force value TH_(c) as afunction, at least in part, of the peak force F_(p). This updated valuecan then be used 46 to determine when excess force is seemingly beingexerted as related above either for this operation or for futureoperations.

So configured, a movable barrier operator will effectively yield anupdated characteristic force value TH_(c) that is substantiallyidentical to the original characteristic force value TH_(c) when adifference as between the original characteristic force value TH_(c) andthe force measurement parameter is within a predetermined minimum range.In a preferred embodiment, the value X can be, for example five percent(5%) of the total typical initial peak force response value as occursduring the initial period 32 of energization. As described, the value Xserves to bound both the upper and lower limits 51 and 52 of this range.If desired, differing values can be used to specify the upper and lowerlimits (this may be appropriate, for example, when seeking to render theoperator more or less sensitive to a peak excursion in a given directionaway from the characteristic force value TH_(c)).

When the actual force response includes a peak that exceeds the minimumrange noted above, in a preferred embodiment the operator will use thatinformation to automatically adjust the characteristic force valueTH_(c) (to thereby effect a change of the excess force threshold value).One approach to guiding the adjustment process appears in FIG. 6.Initially, the operator determines 60 whether the peak force F_(p)exceeds the characteristic force value TH_(c) (in a preferred approach,the operator uses a first determination process 61 when the force peakF_(p) exceeds the characteristic force value TH_(c) and a seconddetermination process 62 when the force peak F_(p) is less than thecharacteristic force value TH_(c)).

Pursuant to the first determination process 61, the operator determines63 whether the force peak F_(p) exceeds a first predetermined threshold.In this embodiment, and referring momentarily to FIG. 7, the firstpredetermined threshold 70 equals the characteristic force value TH_(c)summed with a first predetermined amount Y (wherein Y is larger than thevalue X that establishes the minimum range described earlier).

Referring again to FIG. 6, when the force response 72 has a force peak71 that is less than the first predetermined threshold, the operatoradjusts 64 the characteristic force value TH_(c) by setting the adjustedcharacteristic force value TH_(c) to equal the current peak force F_(p)71. So configured, the characteristic force value TH_(c) automaticallydirectly tracks and corresponds to smaller force peak excursions.Therefore, as force requirements may change via small increments withcircumstance or time, the characteristic force value TH_(c) willsimilarly change. This, of course, leads to a corresponding change ofthe excess force threshold value and hence aids in ensuring thatobstacle detection remains likely accurate and calibrated to currentoperating conditions and circumstances.

Referring again to FIG. 6, when the operator determines 63 that theforce peak F_(p) exceeds the first predetermined threshold, the operatoradjusts 65 the characteristic force value TH_(c) by incrementing theexisting characteristic force value TH_(c) towards the current forcemeasurement without actually reaching the current force measurement. Ina preferred embodiment, this increment corresponds to a step ofpredetermined size or percentage (of either the difference or theabsolute value and as either preset or dynamically calculated asdesired). Therefore, and as illustrated in FIG. 8, when a given forceresponse 80 has a force peak 81 that exceeds the first predeterminedthreshold 70, the characteristic force value TH_(c) is incremented by apredetermined amount K, such that the resultant value 82 will approach,but not necessarily reach the current force peak 81.

So configured, the operator will tend to substantially closely tracksmaller force peaks and more loosely track larger force peaks when theforce peaks exceed the characteristic force value TH_(c) (when coupledwith the minimum range process described earlier, of course, theoperator will essentially ignore minimal force peak variations). Thisapproach permits the operator to automatically maintain an excess forcethreshold value that is substantially current and relevant while alsoavoiding possibly over-significant adjustments that are possibly onlyassociated with anecdotal incidents that may not again occur in the nearterm. (Significant temperature variations can represent one potentialexception to this approach, and additional embodiments described beloware directed to accommodating that circumstance.)

Referring again to FIG. 6, when the operator determines 60 that theforce peak F_(p) does not exceed the characteristic force value TH_(c),the operator utilizes a second determination process 62 to facilitateadjustment of the excess force threshold value. Pursuant to the seconddetermination process 62, the operator determines 66 whether the forcepeak F_(p) is less than a second predetermined threshold.

With momentary reference to FIG. 7, in a preferred embodiment, thesecond predetermined threshold 73 comprises the characteristic forcevalue TH_(c) less a predetermined amount Y (in this embodiment, the samevalue Y is used to determine both the first and second predeterminedthresholds 70 and 73; it would of course be possible to use differentvalues to permit, for example, sensitizing or de-sensitizing theresponse of the process as desired to force response excursions).

Referring again to FIG. 6, when the operator determines 66 that thepresent force peak Fp is not less than the second predeterminedthreshold, the operator sets the present force peak F_(p) value as thenew characteristic force value TH_(c). For example, as illustrated inFIG. 7, a force response 74 having a force peak 75 that falls betweenthe present characteristic force value TH_(c) and the secondpredetermined threshold 73 will cause the adjusted characteristic forcevalue TH_(c) to substantially equal the force peak 75.

When the operator determines 66, however, that the force peak F_(p) isless than the second predetermined threshold, then as shown in FIG. 6,the operator adjusts 67 the characteristic force value TH_(c) bydecrementing or changing the latter towards the current force peak F_(p)by a predetermined step size L. As illustrated in FIG. 8, a forceresponse 83 having a peak 84 that is less than the second predeterminedthreshold 73 will cause the characteristic force value TH_(c) to bedecremented or changed towards the force peak 84 by a step size L. Inthis embodiment, this step size L is smaller than the step size K usedwhen incrementing the characteristic force value TH_(c) towards a largervalue as described above, and it is at least this difference thatdistinguishes the second determination process 62 from the firstdetermination process 61. So configured, the operator can track (closelyor loosely, depending upon the nature of the force peak excursions)changing force needs and reflect those changes in the excess forcethreshold value (by, in these embodiments, adjusting a characteristicforce value TH_(c)). These processes, however, permit more significantimmediate increases in the characteristic force value TH_(c) thandecreases. This preferred approach aids in ensuring that the operatordoes not quickly (and possibly inappropriately) reduce the excess forcethreshold value to a point where the movable barrier cannot be movedwithout triggering a false obstacle detection event.

As described above, the operator can be configured to essentiallyautomatically respond to only a single peak in the force response duringmovement of a movable barrier from a first position to a secondposition, such that adjustment of the characteristic force value TH_(c)(and/or the excess force threshold value) will be essentially based onlyon that one peak and value. For many situations, this approach willprovide satisfactory results. In other instances, however, it may bedesirable to detect and/or respond to more than just this one peak.

For example, and referring now to FIG. 9, a given operator may detect aforce response 90 that is more complex than the simpler responsesillustrated above. As one illustration, in FIG. 9, the force response 90has a first peak plateau 91 that is followed by a second plateau 92 andthen by a third relative plateau 93. With such a force response 90, anexcess force threshold value that tracks the force peak represented bythe first peak plateau 91 may possibly be too high for one or more ofthe later plateau areas 92 or 93. Pursuant to one embodiment, theoperator automatically segments or partitions the force response 90 as afunction of time and determines characteristic force value TH_(c)'s thatcorrespond to each resultant time window. So configured, the resultantcharacteristic force values would then correspond to particular timesduring the time the operator moves the movable barrier and would, in apreferred embodiment, be recalled and utilized at such times. Ifdesired, the number of threshold values (and hence the number ofcorresponding steps) can be fixed at a predetermined level.

For example, and with continued reference to FIG. 9, during the timewindow 94 bounded by time T₁ and T₂, a force response peak thatcorresponds to the first force plateau 91 can be used as described aboveto adjust a characteristic force value TH_(c) for this first time window94. In a similar fashion, during the next succeeding time window 95 (asbounded by time T₂ and T₃), a force response peak that corresponds tothe second force plateau 92 can be used as described above to adjust acharacteristic force value TH_(c) for this second time window 95. In asimilar fashion, other characteristic force values TH_(c) can bedetermined for other corresponding windows of time.

In a preferred embodiment, the number of resultant characteristic forcevalues TH_(c) and the time windows to which such values correlate aredependent upon the force response itself as detected by the operator.For a simple response as illustrated earlier, a single characteristicforce value TH_(c) can be automatically utilized as a satisfactoryguide. For more complicated responses such as the one illustrated inFIG. 9, a plurality of such values can be automatically determined tomore likely ensure ultimate provision of a relevant excess forcethreshold value. In another approach, the number of characteristic forcevalues TH_(c) and/or the specific correlation of such values to specifictimes or barrier positions/locations can be previously determined andset by the manufacturer or installer and/or during a user-initiatedlearning mode of operation.

In the embodiment above, multiple characteristic force values TH_(c) aredetermined with each such value being calculated as a specific functionof a corresponding portion of the force response itself. Pursuant toanother embodiment, a curve can be fit to match, to a greater or lesserextent, the force response. This curve can then be used to permitdynamic determination of a plurality of characteristic force valuesTH_(c).

To illustrate this approach, consider first a force response 100 asdepicted in FIG. 10 that comprises a representative function of theforce exerted by an operator to effect movement of a movable barrierfrom a first position to a second position. It can be seen that a firstforce peak P₁ occurs at approximately time T₁ and that a second relativepeak P₂ occurs at approximately time T₂. These peaks P₁ and P₂ are thenused to establish corresponding characteristic force values TH_(c) asdescribed above. Between the two resultant values, however, a curve isfit to substantially connect such values.

For example, with reference to FIG. 11, a curve 110 can be used toconnect the two peak values P₁ and P₂. This curve 110 can then be usedto permit determination of corresponding characteristic force valuesand/or excess force threshold values. In particular, at any given timebetween T_(1 and T) ₂, the operator can utilize the curve 110 toascertain a corresponding characteristic force value TH_(c) and then usethat value as taught above to determine an excess force threshold valuethat corresponds to that particular time. Various curves can be used asdesired, including exponential curves. In one embodiment, the operatormay have only a single curve definition to use in this manner. Pursuantto another embodiment, the operator may have a plurality of curvedefinitions to choose from. By one preferred approach, the operator cancompare these various resultant curves against the actual force responseto identify a curve that best approximates the actual force response.The curve that best fits the present operating conditions would then beused as otherwise described above. With reference to FIG. 12, it wouldalso be possible to utilize a line 120 to connect the peak values asotherwise described above. Again, such a line might represent a best fitunder some operating conditions.

Undue mechanical resonance (or ringing) can contribute to a resultantcorresponding ringing force response that may not be satisfactorilyaccommodated by the various embodiments set forth above. Such ringingcan occur, for example, when especially heavy barriers are moved. FIG.13 depicts an illustrative ringing force response 130 characterized by aseries of dampening resonant oscillations featuring consecutive peaksand valleys. Upon detecting such a condition (or upon otherwise beinginstructed to operate as now described), the operator then detects thepeaks and valleys of the force response 130 and thereby ascertains atime T_(x) when the ringing phenomena has dampened sufficiently to nolonger represent a significant concern. For example, when the distancebetween a consecutive peak and valley (or valley and peak) is less thana predetermined distance, the operator can conclude that the oscillationhas dampened to a sufficient level. The operator can then select anappropriate curve 140 to represent the force response 130 between aninitial time T₁ and the time T_(x) as illustrated in FIG. 14. Again,various curves can be provided, such that alternative curves 141 can besampled and compared to permit selection of a most appropriate curve.Once selected, the curve can then again be used as described above topermit adjustment of the characteristic force value TH_(c) and/or theexcess force threshold value.

As noted earlier, the initial portion of a force response tends toexhibit a significant transient peak. As already suggested, this initialpeak can be essentially ignored when seeking to automatically set anappropriate threshold to detect an apparent application of excess force.The ordinary occurrence of this phenomena, however, can be used, ifdesired, to ascertain a likely status of the force monitoring sensorand/or the signal pathways that pertain thereto. During time periodssubsequent to the initial peak, it is also possible that force responsepeaks can provide an indication of operational status other than thelikely presence of an obstacle.

With reference to FIG. 15, during a predetermined time period ofinterest 150 (comprising, in this example, the initial time periodduring which the transient force peak ordinarily occurs), the operatordetermines 151 whether the present force measurement exceeds somethreshold T_(F). As suggested by FIG. 16, this threshold T_(F) is set,in a preferred embodiment, considerably lower than the expectedtransient peak 160 (and preferably at a level that is less than theminimum force ordinarily needed to cause selective movement of themovable barrier). When the measured peak exceeds this threshold, theprocess can conclude 152 as set forth in FIG. 15. When, however, theinitial peak 161 is less than the threshold T_(F), and referring againto FIG. 15, the operator can determine 153 a corresponding status andthen optionally take a predetermined action 154. For example, theoperator can conclude that the force sensor is faulty (such a greatlylimited or reduced initial transient response would likely suggest, forexample, a problem or fault with the current sensing resistor or otherrelated electrical failure). The predetermined action 154 could include,for example, not automatically updating the characteristic force valueTH_(c) at this time or as might otherwise be based upon present orimmediately subsequent data.

There also are other conditions that such monitoring of force canpotentially reveal. To illustrate, FIG. 17 depicts a supportiveembodiment. In this embodiment, the excess force threshold value isprovided by an excess force threshold determination unit 171 asotherwise generally related above. In this embodiment, however, theexcess force threshold determination unit 171 further utilizes a maximumforce-setting limit 172. With momentary reference to FIG. 18, thismaximum force-setting limit 172 comprises a limit beyond which theoperator can not automatically drive the characteristic force valueTH_(C). This maximum adaptation limit is larger than either of theearlier adaptation thresholds 51 or 70 described earlier, but is alsosmaller than a physical limit 181 that would otherwise limit thecharacteristic force value TH_(c) (the physical limit 181 being such asthe maximum force that the motor 11 can conceivably deliver under themost favorable of conditions). As a result, the excess force thresholdvalue provided by the excess force threshold determination unit 171essentially comprises a maximum force-setting limited excess forcethreshold value, in that the excess force threshold value itself becomeslimited with respect to the maximum force-setting limit 172. The maximumforce-setting limit can comprise a non-alterable limit or can beotherwise established, such as during a learning mode of operation asdesired and appropriate to a given application.

If desired, and referring again to FIG. 17, the motor controller 10 canalso be made responsive to a fault/stall detector 173. The fault/stalldetector 173 utilizes, in a preferred embodiment, one or more otherthresholds to identify circumstances that likely indicate at least oneof a fault condition and a stall condition. For example, with referenceto FIG. 19, the detector 173 can optionally provide 191 a firstfault/stall detected force indicia threshold and a second 192fault/stall detected force indicia threshold. With reference to FIG. 20,the first such threshold 201 can more specifically comprise an F_(stall)threshold that corresponds to a level of force that likely indicatesthat the motor 11 is stalled. The second such threshold 202 can morespecifically comprise an F_(fault) threshold that corresponds to a levelof apparent force that likely indicates that one or more faults exist inthe force-sensing signal path. Such thresholds can of course be set tocorrespond empirically to a given movable barrier opener.

Referring again to FIG. 19, a maximum force-setting limit 172 can alsobe provided 193 as already earlier described. During normal operation,the operator then determines 194 an excess force threshold value (orvalues as described above) subject to the maximum force-setting limit172 and provided also that the operator will now further determine 195whether a fault/stall condition likely exists based, at least in part,on current force measurements. As illustrated in FIG. 20, the excessforce threshold value F_(R) can be determined 194 by combining thecharacteristic force value TH_(c) with a predetermined offset A (thevalue of A can be selected as appropriate to a given application but ingeneral will serve to provide room for ordinary force peak excursionsthat are not likely indicative of an obstacle while also being smallenough to likely ensure that an obstacle will be detected relativelysoon following impact). As also illustrated (and as otherwise describedabove), the operator will automatically change the characteristic forcevalue TH_(c) as a function, at least in part, of the actual forceresponse. For example, the characteristic force value TH_(c) may bemoved upwardly by an amount B to provide an updated characteristic forcevalue TH_(c) 203 due to such circumstances. When this occurs, thepredetermined offset A is again applied to establish an updated excessforce threshold 204.

So configured, the operator will automatically set an excess forcethreshold value as a function of the measured force response. When theforce response exhibits a peak that exceeds either of the F_(stall) orF_(fault) thresholds, however, the operator will determine 195 that acorresponding stall or fault has occurred and then take an optionalpredetermined action 196. For example, and referring again to FIG. 20,when the force response exceeds the F_(stall) threshold 201, theoperator can cause the motor 11 to reverse 205 and thereby move themovable barrier in an opposite direction. When the force responseexceeds the F_(fault) threshold 202, the operator can cause the motor 11to stop 206 and thereby stop movement (or attempted movement) of themoveable barrier.

It can therefore be seen that a movable barrier operator can monitorforce (typically by monitoring a parameter that itself varies in a waythat corresponds to the apparent application of force) and use thatmeasurement to automatically and dynamically modify an excess forcethreshold during normal operations. In addition, such force monitoringcan be further used to detect various fault conditions and or stalledcircumstances.

As noted earlier, temperature can also significantly impact suchprocesses, at least under some circumstances. For example, current flowrequirements of a motor can increase as ambient temperature drops (atleast during periods when the motor has not recently operated). Suchphenomena is generally suggested in the illustration of FIG. 21. A forceresponse 210 of a given motor at zero degrees Celsius will tend to beconsiderably lower than a force response 211 for that same motor atminus twenty-five degrees Celsius (note that in these illustrations theforce responses 210 and 211 are only shown subsequent to the initialperiod of time during which the transient peak tends to be manifested).Unfortunately, the differences tend to be non-linear. That is, thedifference 212 between the two force responses at one time T₂ will tendto be different than the difference 213 between the two force responsesat a later time T₃. These temperature dependent behaviors present yetadditional challenges to the provision of a successful automaticforce-setting platform.

Therefore, pursuant to another set of embodiments, and referring now toFIG. 22, any of the above embodiments can be modified to furtheraccommodate monitoring 221 both force and temperature (such as ambienttemperature proximal to the motor) and, in conjunction withdetermination 222 of the characteristic force value TH_(c) (and/or theexcess force threshold value) a determination 223 can also be made of atemperature compensation factor to thereby yield a temperaturecompensated excess force threshold value. To facilitate this, andreferring now to FIG. 23, a temperature sensor 232 can serve to providecurrent temperature information to an automatic characteristic forcevalue indicator 231. So configured, the automatic characteristic forcevalue indicator 231 can utilize the temperature information toappropriately compensate the characteristic force value TH_(c) andthereby facilitate the determination of a temperature compensated excessforce threshold value. If desired, of course, it would also be possibleto provide the temperature information to the automatic excess forcethreshold value indicator 15 and provide for temperature compensationdirectly to the latter.

There are a number of ways to effect such an approach. With reference toFIG. 24, pursuant to one embodiment, current temperature is measured 241and then compared 242 against a first condition. In this embodiment, thefirst condition prompts a determination as to whether the currenttemperature is less than a predetermined value, such as zero degreesCelsius. When true, the characteristic force value TH_(c) is immediatelyset 243 to the current peak force (regardless of whether smallermovements would have otherwise been utilized pursuant to any of theabove embodiments). (The characteristic force value TH_(c) can be set inthis fashion on either a temporary basis (such as only for the presentoperation) or until otherwise changed pursuant to the other teachingsset forth herein as appropriate to a given application.) When thecurrent temperature does not meet the first condition, the process nextdetermines 244 whether the current temperature is substantiallydifferent than a previously measured temperature as corresponds to aprevious force peak that was previously utilized to facilitateadjustment of the excess force threshold value. When true, therebyindicating that a substantial difference in temperature exists asbetween the present setting and a most recent prior setting, the processagain sets the characteristic force value TH_(c) to equal the currentforce peak (as before, this change can be temporary, such as for only asingle operation, or of a potentially more lasting nature). Otherwise,when the present temperature and prior temperature are not significantlydifferent from one another, the characteristic force value TH_(c) is setto a different value, albeit one that may still be temperaturecompensated.

In general, as the temperature drops, the temperature compensation willtend to comprise an ever-increasing additive value that the processcombines with the characteristic force value TH_(c) (and/or the excessforce threshold value) to thereby increase the resultant excess forcethreshold value. Pursuant to a preferred embodiment, the followingequation can be utilized to determine the magnitude of this additivevalue when the characteristic force value TH_(c) is not otherwise simplyset to equal the current force peak.${{Temperature}\mspace{14mu}{compensation}\mspace{14mu}{value}} = {\frac{{MTF} - {TH}_{c}}{8} \cdot \frac{{Temp}({diff})}{K}}$where:

-   MTF=a maximum upper threshold boundary;-   TH_(c)=current characteristic force value;-   Temp(diff)=the current temperature less the previous temperature;    and-   K=a constant that corresponds to the temperature sensor 232 itself    (such as when the sensor comprises a thermistor).

This equation will tend to produce a higher value as the ambienttemperature drops quickly by a significant amount. Referring now to FIG.25, in an alternative approach using temperature compensation, theoperator first determines 251 whether the current temperature is lessthan a predetermined amount X (such as, in a preferred embodiment, zerodegrees Celsius). If not, temperature differences often lendconsiderably less impact upon force and/or force sensing and hencenormal 252 processing sans temperature compensation as described earlierwill proceed. When the current temperature falls below the desiredthreshold, however, the operator measures 253 force. For purposes ofthis particular activity, the force need only be measured subsequent tothe initial time period during which the characteristic transient peakordinarily occurs. The operator then determines 254 whether the currentmeasured force exceeds the current characteristic force value TH_(c) ascombined with a current temperature compensation value (wherein thecurrent temperature compensation value can be calculated or otherwiseobtained as described above). When true, the process continues in normalfashion (wherein the characteristic force value TH_(c) is combined withthe temperature compensation value and the excess force threshold valueis determined accordingly). When the current peak force is less than thecharacteristic force value TH_(c) as combined with the temperaturecompensation value, however, this process then sets 255 thecharacteristic force value TH_(c) to equal the current force peak. Soconfigured, the process will permit ordinary temperature compensationwhen significant differences are not present but will prompt rapidsignificant alteration when significant force differences are presentunder these conditions.

With reference to FIG. 26, yet another temperature compensation approachhas the operator again measure 261 the current temperature and determine262 whether it is cold enough to warrant temperature compensation. Ifnot cold enough, the temperature compensation process can simplyconclude 263. When it is cold enough, however, the operator thendetermines 264 a temperature differential TEMP(delta) by determining adifference between a previous temperature TEMP(ref) (as ordinarilycorresponds to a previously utilized force measurement) and the currenttemperature. The operator then determines 265 whether this differenceexceeds a predetermined amount Y (such as, in a preferred approach, 2.5degrees Celsius). If not, then ordinary temperature compensation via useof a temperature compensation adder value can continue as describedabove. When the difference exceeds this predetermined amount, theoperator facilitates rapid force-setting compensation by adopting 266the current force peak as the updated characteristic force value TH_(c)(while also establishing the current temperature as the referencetemperature for use in a subsequent iteration of this same process). Soconfigured, ordinary incremental temperature compensation can beutilized at colder temperatures with an immediate significant alterationto the characteristic force value when a significant shift intemperature during a colder interval occurs. In a preferred embodiment,such an immediate significant alteration will comprise the onlyforce-setting alteration made during this corresponding cycle.

As mentioned earlier, runtime for the motor 11 can also impact accurateassessment of force, and particularly so during colder temperatures.Pursuant to yet another embodiment the operator can compensate for suchphenomena. With reference to FIG. 27, the operator can optionallydetermine 271 whether the current temperature is less than apredetermined threshold X (in a preferred embodiment, X equals zerodegrees Celsius). With warmer temperatures, the operator can typicallydispense with any need for running motor compensation and simply proceedwith normal 272 automatic force-setting procedures as related herein. Atcolder temperatures, however, the operator then determines 273 whetherthe motor 11 has had a predetermined operational state for more than apredetermined period of time Y. In a preferred approach, the operatordetermines 274 whether the motor 11 has been off for more than the timeY (Y can be selected as appropriate to a given application and generallyshould be no less than a period of time, such as thirty to sixtyminutes, during which a motor will reach a quiescent state with respectto these phenomena).

When the motor 11 has been off for more than the time Y, the operatordetermines 274 an appropriate runtime adder value (or values asappropriate to the application). With momentary reference to FIG. 28,these adder values can be dynamically determined if desired or by accessto an appropriate look-up table or similar mechanism. In general, theseadder values comprise force values that are suitable to add to thecharacteristic force value to yield a suitably motor runtime compensatedcharacteristic force value. Such adder values will vary with the currenttemperature and further vary over time (the length of time that themotor has been running). Two exemplary adder value curves are shown inthis figure, comprising a first curve 281 for minus 40 degrees Celsiusconditions and a second curve 282 for minus 20 degrees Celsiusconditions. It can be seen that, in general, the adder value is largerat lower temperatures and at lower durations of runtime for the motor.When a motor has been off for the predetermined period of time, theadder value will begin at time zero and with a curve that most closelycorresponds to the current temperature (a large number of such curvescan be determined and stored or, in the alternative, a few such curvescan be stored and interpolation utilized to determine specific addervalues for a given current temperature). So configured, an appropriateadder value is determined for a specific point in time (for example, atminus forty degrees Celsius and at time T_(n), a specific correspondingpoint 283 on the corresponding curve 281 will comprise the motor runtimeadder value).

Referring again to FIG. 27, when the motor has not been off for thepredetermined period of time (meaning usually that the motor was justrecently used), the operator determines 275 an appropriate offtimecorrection value. In particular, and referring now to FIG. 29, a similarset of curves are provided for various ambient temperature conditions(with one such curve 291 for minus forty degrees Celsius being shown inthis illustration). So configured, an appropriate time location isdetermined (as corresponds to how long the motor has been off sincehaving just recently been on), such as time T_(n), and the correspondingpoint 292 on the appropriate curve 291 again utilized to determine anappropriate motor offtime correction value.

Referring again to FIG. 27, the operator then uses the runtime addervalue or the offtime correction value to determine 276 a characteristicforce value that comprises a motor compensated characteristic forcevalue. The latter can then be utilized as otherwise described above topermit eventual provision of a motor runtime compensated excess forcethreshold value.

Pursuant to these various embodiments, a movable barrier operator caneffect automatic force-setting with or without a user-initiated learningmode and/or a user manipulable force-setting interface. Such automaticforce-setting can loosely or closely follow force peak excursions thatdo not otherwise appear to evince a problem. The force-setting processcan be compensated to account for variations that are ordinarilyassociated with environmental conditions such as temperature as well aswith operational status such as motor runtime. In addition, the operatorcan utilize such force measurements to ascertain other potentialconditions of concern, including faulty components and stalling. Suchbenefits accrue with only a modest addition of corresponding sensor(s)and/or other components or programming and tend to assure that anauto-force setting movable barrier operator can reliably detect andrespond to an obstacle under a variety of changing operationalcircumstances.

Those skilled in the art will recognize that a wide variety ofmodifications, alterations, and combinations can be made with respect tothe above described embodiments without departing from the spirit andscope of the invention, and that such modifications, alterations, andcombinations are to be viewed as being within the ambit of the inventiveconcept.

1. A movable barrier operator for use with a movable barrier, whichmovable barrier is selectively moved through selective application offorce by a motor via the movable barrier operator, wherein the motor hasa corresponding range of output forces, the movable barrier operatorcomprising: at least one force sensor; a maximum force-setting limitthat is within the corresponding range of output forces; an excess forcethreshold determination unit that is responsive to the maximumforce-setting limit and having a maximum force-setting limited excessforce threshold value output, wherein the excess force thresholddetermination unit comprises an automatic excess force thresholddetermination unit that is responsive to the maximum force-setting limitand having an automatically determined maximum force-setting limitedexcess force threshold value output; a movable barrier obstacle detectorthat is at least partially responsive to the at least one force sensorand to the maximum force-setting limited excess force threshold valueoutput; and a motor controller operably coupled and responsive to themovable barrier obstacle detector.
 2. The movable barrier operator ofclaim 1 and further comprising a fault-detected force indicia threshold,which fault-detected force indicia threshold exceeds the maximumforce-setting limit.
 3. The movable barrier operator of claim 1 andfurther comprising a fault-detected force indicia threshold, whichfault-detected force indicia threshold is less than a minimum forceneeded to cause selective movement of the movable barrier.
 4. Themovable barrier operator of claim 1 and further comprising: a firstfault-detected force indicia threshold, which first fault-detected forceindicia threshold exceeds the maximum force-setting limit; and a secondfault-detected force indicia threshold, which second fault-detectedforce indicia threshold is less than a minimum force needed to causeselective movement of the movable barrier.
 5. The movable barrieroperator of claim 1 wherein the maximum force-setting limit comprises anon-alterable limit.
 6. The movable barrier operator of claim 1 whereinthe maximum force-setting limit is set during a movable barrier operatorlearning mode of operation.
 7. The movable barrier operator of claim 1wherein the maximum force-setting limit comprises one of: a defaultpreset value; and a dynamically set value.
 8. A method for use with amovable barrier operator that controls a motor having a correspondingrange of force values, comprising: providing a maximum force-settinglimit that is within the corresponding range of output forces of themotor; monitoring at least one parameter that corresponds to force asapplied by the motor to selectively cause a movable barrier to move;limiting an excess force threshold value such that an updated excessforce threshold does not exceed the maximum force-setting limit; usingthe updated excess force threshold value and the at least one parameterto determine when excess force is being applied to the movable barriervia the movable barrier operator; taking a predetermined action whenexcess force is seemingly being applied to the movable barrier via themovable barrier operator; providing a fault-detected force indiciathreshold, when fault-detected force indicia threshold exceeds themaximum force-setting limit.
 9. The method of claim 8 wherein limitingan excess force threshold value includes automatically changing anexcess force threshold value in response to the monitored at least oneparameter to provide the updated excess force threshold value, whereinthe updated excess force threshold does not exceed the maximumforce-setting limit.
 10. The method of claim 8 and further comprisingproviding: a first fault-detected force indicia threshold, which firstfault-detected force indicia threshold exceeds the maximum force-settinglimit; and a second fault-detected force indicia threshold, which secondfault-detected force indicia threshold is less than a minimum forceneeded to cause selective movement of the movable barrier.
 11. Themethod of claim 8 wherein providing a maximum force-setting limitincludes providing a non-alterable maximum force-setting limit.
 12. Themethod of claim 8 wherein providing a maximum force-setting limitincludes determining the maximum force-setting limit during a learningmode of operation.
 13. The method of claim 8 wherein providing a maximumforce-setting limit includes using one of: a default preset value; and adynamically set value.
 14. A movable barrier operator for use with amovable barrier, which movable barrier is selectively moved throughselective application of force by a motor via the movable barrieroperator, the movable barrier operator comprising: at least one forcesensor; an automatically determined obstacle-detected force indiciathreshold; a stall-detected force indicia threshold; a fault-detectedforce indicia threshold; a movable barrier obstacle detector that is atleast partially responsive to the at least one force sensor and to theautomatically determined obstacle-detected force indicia threshold; anda motor controller operably coupled and responsive to the movablebarrier obstacle detector and to the at least one force sensor, whereinthe motor controller causes the motor to take a specific predeterminedaction whenever a current measured force exceeds any of theautomatically determined obstacle-detected force indicia threshold, thestall-detected force indicia threshold, and the fault-detected forceindicia threshold.
 15. The movable barrier operator of claim 14 whereinthe specific predetermined action includes: reversing operation of themotor when the current measured force exceeds the automaticallydetermined obstacle-detected force indicia threshold; reversingoperation of the motor when the current measured force exceeds thestall-detected force indicia threshold; and stopping operation of themotor when the current measured force exceeds the fault-detected forceindicia threshold.
 16. A method for use with a movable barrier operator,comprising: monitoring at least one parameter that corresponds to forceas applied by a motor to a movable barrier to selectively cause themovable barrier to move; providing an automatically determinedobstacle-detected force indicia threshold; providing a stall-detectedforce indicia threshold; providing a fault-detected force indiciathreshold; taking a predetermined corresponding action when theparameter that corresponds to force exceeds any of the automaticallydetermined obstacle-detected force indicia threshold, the stall-detectedforce indicia threshold, and the fault-detected force indicia threshold.17. The method of claim 16 wherein taking a predetermined correspondingaction when the parameter that corresponds to force exceeds any of theautomatically determined obstacle-detected force indicia threshold, thestall-detected force indicia threshold, and the fault-detected forceindicia threshold includes: reversing operation of the motor when theparameter exceeds the automatically determined obstacle-detected forceindicia threshold; reversing operation of the motor when the parameterexceeds the stall-detected force indicia threshold; and stoppingoperation of the motor when the parameter exceeds the fault-detectedforce indicia threshold.
 18. A method for use with a movable barrieroperator, comprising: monitoring at least one parameter that correspondsto force as applied to a movable barrier by a motor to selectively causethe movable barrier to move; automatically changing an excess forcethreshold value in response to the monitored at least one parameter toprovide an updated excess force threshold value; using the updatedexcess force threshold value and the monitored at least one parameter todetermine when excess force is seemingly being applied to the movablebarrier via the movable barrier operator; taking a predetermined actionwhen excess force is seemingly being applied to the movable barrier viathe movable barrier operator; determining that a predetermined statuslikely exists when the at least one parameter that corresponds to forceas measured during a predetermined time period that corresponds toinitial energization of the motor meets at least one predeterminedcriteria; determining that at least a particular level of operationalforce has been sensed during the predetermined time period when amonitored temperature is within a predetermined range.
 19. The method ofclaim 18 wherein determining that a predetermined status likely existsincludes determining that a fault condition likely exists.
 20. Themethod of claim 18 wherein only using such determination when amonitored temperature is within a predetermined range includes onlyusing such determination when a monitored temperature is less than zerodegrees Celsius.
 21. A method for use with a movable barrier operator,comprising: monitoring at least one parameter that corresponds to forceas applied to a movable barrier by a motor to selectively cause themovable barrier to move; automatically changing an excess forcethreshold value in response to the monitored at least one parameter toprovide an updated excess force threshold value; using the updatedexcess force threshold value and the monitored at least one parameter todetermine when excess force is seemingly being applied to the movablebarrier via the movable barrier operator; taking a predetermined actionwhen excess force is seemingly being applied to the movable barrier viathe movable barrier operator; determining that a fault condition existswhen the at least one parameter that corresponds to force fails toattain at least a first threshold during a predetermined time periodthat includes a period of time when the motor first becomes energizedand is at least one second in duration.
 22. A method for use with amovable barrier operator, comprising: monitoring force as the movablebarrier operator causes a movable barrier to move from a first positionto a second position to provide a representative function of the force;determining only a single force value to serve as a characteristic forcevalue for the movable barrier operator when the monitored force meets afirst predetermined criteria; determining a plurality of force values toserve as a plurality of characteristic force values for the movablebarrier operator when the monitored force does not meet the firstpredetermined criteria; determining the plurality of force values as afunction of the representative function of the force.
 23. The method ofclaim 22 and further comprising using whichever one of thecharacteristic force value and the plurality of characteristic forcevalues has been determined to facilitate detection of excess force asapplied to the movable barrier.
 24. A movable barrier operator for usewith a movable barrier, comprising: at least one sensor to sense aparameter that corresponds to force as is apparently applied to at leastattempt to move the movable barrier; a first characteristic force valuethat has been determined as a function of sensed force as is apparentlyapplied to move the movable barrier from a first position to a secondposition; at least a second characteristic force value that has beendetermined as a function of sensed force as is apparently applied tomove the movable barrier from a first position to a second position; anobstacle detector responsive to the at least one sensor and, withrespect to at least one of time and position of the movable barrier, tothe first and second characteristic force values, and having an obstacledetected output that corresponds to an apparent application of excessforce to the movable barrier; wherein using the first and secondcharacteristic force values includes representing at least one of thefirst and second characteristic force values as a combination of anincremental value and another characteristic force value.
 25. A methodfor use with a movable barrier operator that controls a motor having acorresponding range of force values, comprising: providing a maximumforce-setting limit that is within the corresponding range of outputforces of the motor; monitoring at least one parameter that correspondsto force as applied by the motor to selectively cause a movable barrierto move; limiting an excess force threshold value such that an updatedexcess force threshold does not exceed the maximum force-setting limit;using the updated excess force threshold value and the at least oneparameter to determine when excess force is seemingly being applied tothe movable barrier via the movable barrier operator; taking apredetermined action when excess force is seemingly being applied to themovable barrier via the movable barrier operator; providing afault-detected force indicia threshold, which fault-detected forceindicia threshold is less than a minimum force needed to cause selectivemovement of the movable barrier.
 26. The method of claim 25 whereinlimiting an excess force threshold value includes automatically changingan excess force threshold value in response to the monitored at leastone parameter to provide the updated excess force threshold value,wherein the updated excess force threshold does not exceed the maximumforce-setting limit.
 27. The method of claim 25 and further comprisingproviding: a first fault-detected force indicia threshold, which firstfault-detected force indicia threshold exceeds the maximum force-settinglimit; and a second fault-detected force indicia threshold, which secondfault-detected force indicia threshold is less than a minimum forceneeded to cause selective movement of the movable barrier.
 28. Themethod of claim 25 wherein providing a maximum force-setting limitincludes providing a non-alterable maximum force-setting limit.
 29. Themethod of claim 25 wherein providing a maximum force-setting limitincludes determining the maximum force-setting limit during a learningmode of operation.
 30. The method of claim 25 wherein providing amaximum force-setting limit includes using one of: a default presetvalue; and a dynamically set value.
 31. The method for use with amovable barrier operator, comprising: monitoring at least one parameterthat corresponds to force as applied to a movable barrier by a motor toselectively cause the movable barrier to move; automatically changing anexcess force threshold value in response to the monitored at least oneparameter to provide an updated excess force threshold value; using theupdated excess force threshold value and the monitored: at least oneparameter to determine when excess force is seemingly being applied tothe movable barrier via the movable barrier operator; taking apredetermined action when excess force is seemingly being applied to themovable barrier via the movable barrier operator; determining that afault condition exists when the at least one parameter that correspondsto force fails to attain a peak value that exceeds a first thresholdduring a predetermined time period.
 32. A method for use with a movablebarrier operator, comprising; monitoring force as the movable barrieroperator causes a movable barrier to move from a first position to asecond position; determining only a single force value to serve as acharacteristic force value for the movable barrier operator when themonitored force meets a first predetermined criteria; determining aplurality of force values to serve as a plurality of characteristicforce values for the movable barrier operator when the monitored forcedoes not meet the first predetermined criteria; representing at leastone of the plurality of characteristic force values as a combination ofan incremental value and another of the characteristic force values. 33.The method of claim 32 and further comprising using whichever one of thecharacteristic force value and the plurality of characteristic forcevalues has been determined to facilitate detection of excess force asapplied to the movable barrier.